A carpet manufacturer selects a specific market or end use for the carpets that he will manufacture before selection of a method of manufacture (machine), raw materials to be used (yarn, backing, dyeing, finishing and secondary backing).
There are three distinct end uses for carpets:
1. Residential PA1 2. Commercial or Industrial PA1 3. Specialty Uses such as marine, automotive, acoustic etc. PA1 1. superior recovery from crushing or compression PA1 2. the ability to be tufted at high speeds PA1 3. the ability to apply desired color on conventional dyeing equipment at atmospheric pressure PA1 4. strength to resist heavy foot traffic PA1 5. a good bulking characteristic to give coverage without using too much material (texturing potential)
Each end use requires raw materials made up specifically for that use. For example, a thick luxurious carpet pile is very desirable in a residential living area but it would not last very long in an office or a high traffic restaurant. The method of manufacture and the materials used must match the end use.
Residential Carpet:
There are three basic types of Residences that use residential carpets: (a) Private Individual Home, (b) Apartment dwellings, (c) Modular or mobile homes.
Most residential carpet (comprising 68% of the total market) is made using nylon yarns for the face or pile that are curled by the Bulked Continuous Filament process or by a Crimping Process that imparts wool-like curls to the yarn. The carpet is usually colored after by being piece dyed in a beck or on a continuous dye process range. This type of carpet is dyed to brilliant shades to match popular decors found in the home. Living room and bedroom carpeting is usually a thick cut pile type of carpet whereas the remainder e.g. the playroom, den and basement is usually carpeted using a loop pile. Thickness of pile varies with the income level of the purchaser but in general, expensive homes use thick pile carpets of nylon in solid shades, while mobile homes and apartments use a thinner pile carpet and will use multi-color cut pile or loop piles. 98% of all residential carpets are manufactured using tufted methods and synthetic carpet yarn in the face. The primary and secondary backing is manufactured using synthetic woven polypropylene. In addition, carpets that are woven or manufactured using a needlebonded process are also used as residential carpets. Needlebonded carpets use crimped staple carpet fibers that have been manufactured by cutting many strands of crimped continuous filaments into lengths that vary from 2.5 inches to 7.5 inches.
Most residential carpet is now manufactured by multiple manufacturers using similar raw materials and methods. There is very little that differentiates one manufacturer's carpet from another. Cost and pricing is the driving force that enables one manufacturer to gain market share over another. Economies of scale have reduced the manufacturing costs to a level that is almost equal among manufacturers. The only way to achieve a cost advantage would be to select a face yarn that would create the look and feel of present day carpets yet cost less to manufacture. A manufacturer that uses a new cost savings material in the face of the carpet would have a distinct advantage.
Commercial Carpet:
Commercial carpet is used in buildings that are not considered residential in nature. Offices, Halls, Medical Facilities, Restaurants, Hotels, Schools and the like fall into this category. Aircraft, automobiles, recreational vehicles and boats are another important commercial category.
Carpet Used in Commercial Buildings:
Commercial carpet in buildings is characterized by a very dense construction and is usually made in a level loop pile. Approximately 98% of the commercial carpet in the United States is tufted. Woven and Needlebonded carpets are also used as commercial carpets. The face yarn of commercial carpet is usually pre-colored before it is tufted or woven into carpets. The pre-colored yarns are usually blended or twisted together to create a multi-colored or heather type of yarn. Pre-colored yarn using a pigmented dye method is more color fast and fade resistant than carpet colored by the piece dye system. However a growing segment of the commercial market is in print carpet. Commercial carpets made using nylon face carpet yarns are printed on a large scale printing machine to create patterns that resemble more expensive Axminster woven styles.
Nylon and polypropylene are used in 97.7% of all commercial carpeting. The same economics that influence residential market cost and pricing also influences the commercial markets. A manufacturer that can save on raw materials in the carpet face yarn will have a great advantage.
It will be shown herein that by using the concepts of the present invention, a manufacturer can create carpets to suit either a residential or commercial application and obtain a substantial cost advantage by using face yarns that look and perform like nylon or pre-colored carpet face yarns yet cost less to manufacture. These new carpets can be processed on nylon carpet dyeing and processing equipment without modification.
The present invention relates primarily to a new bulked (textured) continuous filament dyeable carpet face yarn that utilizes a sheath-core melt spinning process. This carpet yarn is a multi filament yarn comprised of a plurality of individual uniformly sheath-cored filaments having a dyeable sheath of virgin Nylon and a carpet grade polymer core that cannot be dyed using standard nylon dye atmospheric pressure dyeing methods. This yarn is a less expensive substitute for 100% Nylon carpet face yarn.
The bicomponent filament yarn of present invention finds its principal application in the tufted carpet industry which utilizes undyed yarns as face yarns to create tufted carpet greige goods. In the manufacture of tufted carpeting, the face yarns used in the process, account for at least 68% of the cost of the finished product. Another significant cost when manufacturing carpet is the dyeing of the carpet. Dyeing nylon carpet is usually achieved by a standard atmospheric dyeing process. In this dyeing process, the carpet is subjected to a bath which contains dyes, chemicals and water at elevated temperatures. The dye attaches chemically to the nylon yarn dye sites and the result is a desirable color shade. Face yarn constitutes the major portion of carpet manufacturing expense while the dyeing of the carpet is the next most expensive manufacturing step.
There are two common types of synthetic dyeable carpet face yarn available to the tufted carpet industry, polyester and Nylon. The Nylon yarns are dyeable at standard atmospheric pressure. Polyester is dyeable by using expensive pressure vessels and harsh chemical carriers. Polyester has no dye sites and therefore is uhdyeable using the nylon acid dye system. The tufted carpet industry uses 90% Nylon as face yarns to manufacture carpet dyeable at atmospheric pressure. Nylon yarn is dyeable because dye sites are present in its manufacture. These dye sites are receptive to the most common acid dyes used in the tufted carpet industry. Nylon yarns are called by the generic trade name, Nylon. There are two common trade names for nylon, nylon 6 or nylon 6/6. Both are dyeable using standard atmospheric pressure in concert with acid dyes. They are well known to those skilled in the art.
As Reader says in U.S. Pat. No. 4,406,310, "Since carpets must be both functional and aesthetic the characteristics of the face yarns inserted into the fabric and the ability to apply desired colors to such yarns and tufted carpets and the tufting design are very important in determining marketability of the final carpets." In addition to ease of dyeing, carpeting must withstand repeated stress under various traffic pressure. Because Nylon stands up to heavy traffic and its ease of dyeing, it is the yarn of choice in the tufted carpet industry. Nylon is the primary raw material for approximately 68% (1.9 billion pounds) of the total synthetic tufted carpet industry.
Synthetic fibers and yarns are based on the petrochemical industry. The chemicals necessary to manufacturer Nylon are a product of the oil refining process and increase in price in direct proportion to the price of oil. Nylon is only available from a limited number of large manufacturers. This limited number of suppliers is due to the capital intensive equipment required to polymerize nylon. Although it would be obviously desirable to use a less expensive substitute for carpet nylon, the solution to this problem has been difficult to achieve.
Specifically, to qualify as a nylon substitute face yarn in the tufted carpet industry, the yarn must have the following characteristics:
No other synthetic carpet material except nylon possesses all the above named five desired qualities.
The manufacturer of tufted nylon carpet can also achieve many desirable color effects from undyed greige goods. For example, nylon carpet can be dyed into many different shades of solid colors, printed with floral or geometric designs, or sprayed with computer assisted equipment for tonal effects. When using nylon other special effects can be achieved in the dyeing and treatment of the yarn. This includes the application of stain repellents, anti-microbial and multi-colored space dyeing.
Sheath-core techniques using different polymers and cross sections are well known to produce yarn characteristics which may be desirable for specific applications such as tire treads, seat belts, apparel, etc. but which are entirely unsuitable for carpet manufacture and in particular, the manufacture of bulked continuous filament carpet yarn or crimped staple carpet fibers.
The following are some examples:
The Matsui U.S. Pat. No. 3,700,544 teaches improved filament flexural rigidity due to appropriate non-circular shapes given to the core. Matsui's examples all specify quenching the drawn filaments in 100 centigrade water for between ten and fifteen minutes. Such conditions are impractical for the commercial production of carpet yarn.
Lin Fa Lee U.S. Pat. No. 3,992,499 shows that it is possible to extrude two filaments of differing dyeability using a sheath core system of feeding two molten polymers to a special spinneret. The patent teaches how to dye heather effects for apparel by varying the amount of polymer having differing dye receptors. The yarn sizes in each example limit its use to apparel applications and does not teach any practical carpet yarn applications to one skilled in the art.
Hull U.S. Pat. No. 3,803,453 teaches that a polyethylene sheath with a core of carbon can be co-extruded with nylon to create a synthetic filament having electrically conductive properties to eliminate static. However, the construction of this filament limits its use to that of an additive to a carpet face yarn. It cannot physically function as a carpet face yarn, in particular as a bulked face yarn.
van Leeuwen et al. U.S. Pat. No. 4,473,617 teaches a bicomponent multi filament that has a pigmented core and an outer sheath of nylon having a high tenacity suitable for use in seat belts, fishing nets and ropes. The outer nylon sheath protects manufacturing equipment for seat belts, nets and rope from abrasive additives to the core. This invention has no applicability to the manufacture of bulked continuous filament carpet face yarn since the abrasive additives in the core prohibit texturization of these filaments.
Saito et al. U.S. Pat. No. 4,987,030 teaches that by melt spinning a bicomponent sheath core process using a high intrinsic viscosity polyethylene terephthalate core and a Nylon sheath composed mainly of polyhexamethylene adipamide (Nylon 6/6) it is possible to produce a superior tire cord yarn that has excellent adhesion to rubber. The specifications call for a core material using a high IV of preferably 0.90 and yielding a high tenacity conjugated fiber. The high intrinsic viscosity raw material which Saito uses is much too expensive to be used in the manufacture of carpet yarn. The high tenacity requirement for tire cord yarn is not required for a carpet face yarn.
Schipper et al. U.S. Pat. No. 4,019,311, uses the principles of bicomponent sheath-core and side by side extrusion. The concept clearly states that a stretch ratio of 1:1.25 to 1:2.5 be maintained in order to achieve the desired results. The invention uses the second stage of stretching to break filaments causing them to twist around the other dissimilar filaments thus producing a yarn that feels as if it were mechanically spun from staple tow. Schipper relies on using two filaments that have different stretch potentials. One filament is fully stretched and breaks when drawn further in a second step while the other does not break and is used as a vehicle to carry the broken filaments. This is shown clearly in FIG. 4 where an edge roller is used to draw stretch and break some filaments. While this concept may be useful in the apparel and sweater trade, the weakness of the yarns produced using this method would prohibit them from being used as a carpet yarn.
While teaching specific sheath-core technology techniques the forgoing patents do not address the characteristics necessary for the manufacture of a dyeable carpet face yarn. More specifically, both cost and performance characteristics of each of the above prohibit teaching or suggesting use as commercial carpet yarns.